We don't really have the space but if I were to get involved in something like that it would need to be done properly through an organisation such as your school.

In the UK if you were taking in a minor (under 16) it would be a good idea for everyones benefit to ensure that it was done properly with appropriate criminal record checks etc. I think that may be compulsory anyway as the person you would stay with would have to take 'parental' responsibility for you for the time you are here.

Andy